1. Field of the Invention
This invention pertains to filtration, and more particularly to replaceable filter assemblies.
2. Description of the Prior Art
Various equipment has been developed to filter fluids of different viscosities. A well-known type of filter is the bag filter, wherein the filter medium is generally in the form of a flexible bag suspended within a fluid-impervious housing. The filter bag may be of the self-supporting type, or it may be enclosed within a basket that provides mechanical strength against the pressure differential created by the fluid being forced through the bag.
Advantages of bag filters include their relatively low cost and their ability to handle large volumes of fluid. On the other hand, a reoccurring problem with bag type filters involves the mounting and retention of the filter medium within the housing. An essential criterion is that the fluid must not bypass the filter medium. Consequently, a highly effective seal is required between the filter medium and the housing interior. At the same time, the filter medium must be easily removable from the housing for servicing or replacement.
The opposed requirements of effective sealing and easy accessibility pose a design problem that has not been solved in a completely satisfactory manner. In a certain commercial product, the filter bag is sealed against both the housing and a housing cover. That design has the drawback of requiring the filter basket and filter bag to be installed and removed from the housing as individual pieces. In addition, the sealing areas between the filter bag, housing, and cover are hidden from view when assembled, thereby preventing inspection of the seal between the bag and housing.
Thus, a need exists for improved sealing in bag filters.